Just bought one of these and installed it yesterday. After I changed to the Trick-flow lower and Hogan upper I felt that the car feltlike it had a bog @2500rpm. not a real big deal but... The dyno #'s I made were with GT40 heads and a Cobra intake so with the new setup I think I pumped up the power, and leaving the timing the way I had it with the spout locked out @20 degrees was what my problem was. Sure enough this thing worked awesome,it maintains factory timing until boost then locks it where ever you set it. Excellent street mannners now, not that it was unbearable before, just slightly irritating and for $150.00 I had to give it a try.